Description of mechanism that halts solar eruptions

This solar flare occurred at the peak of the solar cycle in October 2014 with no observed eruptions. PPPL researchers say this is a promising candidate for studying the effect of guide magnetic fields. Credit: NASA

Among the most feared events in space physics are solar eruptions, massive explosions that hurl millions of tons of plasma gas and radiation into space. These outbursts can be deadly: if the first moon-landing mission had encountered one, the intense radiation could have been fatal to the astronauts. And when eruptions reach the magnetic field that surrounds the Earth, the contact can create geomagnetic storms that disrupt cell phone service, damage satellites and knock out power grids.

NASA is eager to know when an eruption is coming and when what looks like the start of an outburst is just a false alarm. Knowing the difference could affect the timing of future space missions such as journeys to Mars, and show when steps to protect satellites, power systems and other equipment need to be taken.

At the U.S. Department of Energy's Princeton Plasma Physics Laboratory (PPPL), researchers led by physicist Clayton Myers have identified a mechanism that may halt eruptions before they leave the sun. The finding, reported in the December 24-31 issue of Nature magazine, provides a potentially important way to distinguish the start of explosions from buildups that will fail. This work was supported by the DOE office of Science.

The violent eruptions, called "coronal mass ejections," stem from a sudden release of magnetic energy that is stored in the sun's corona, the outermost layer of the star. This energy is often found in what are called "magnetic flux ropes," massive arched structures that can twist and turn like earthly twine. When these long-lived structures twist and destabilize, they can either erupt out into the solar system or fail and collapse back toward the sun.

The researchers found in laboratory experiments that such failures occur when the guide magnetic field—a force that runs along the flux rope—is strong enough to keep the rope from twisting and destabilizing. Under these conditions, the guide field interacts with electric currents in the flux rope to produce a dynamic force that halts the eruptions. PPPL has discovered the importance of this force, called the "toroidal field tension force," which is missing from existing models of solar eruptions.

The researchers discovered this importance using the Laboratory's Magnetic Reconnection Experiment (MRX), the world's leading device for studying how magnetic fields in plasma converge and violently snap apart. The scientists modified the device to produce both a flux rope, which stores a significant amount of energy that seeks to drive the rope outward, and a "potential magnetic field" like the ones that enclose the rope in the solar corona.

This potential magnetic field is composed of magnetic "strapping" and "guide" fields, each of which provides restraining forces. Eruptions burst forth when the restraining forces in the strapping field become too weak to hold the rope down, creating what is called a "torus instability" that shoots plasma into space. The guide field, which reduces the twist in the flux rope, had long been thought to be of secondary importance.

But the researchers found that the guide field can play an important role in halting eruptions. When the flux rope starts to move outward in the presence of a sufficiently powerful guide field, the plasma undergoes an internal reconfiguration—or "self-organization"—that causes the eruption to lose energy and collapse. "The presence of a substantial guide field should therefore indicate a reduced probability of eruption," said Myers.

Solar physicists should thus be on the lookout for guide fields, which can be found in relatively simple reconstructions of the sun's potential magnetic field. One promising candidate for study is the largest active region in the peak solar cycle that took place in October 2014, which produced many large flares but no observed eruptions. Preliminary analysis of this region shows that a number of these flares were associated with failed eruptions that could have been caused by the mechanism the MRX experiments found.

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16 comments

The prevailing belief is that the outcome of a given event is determined by a magnetohydrodynamic force imbalance called the torus instability. This belief is challenged, however, by observations

No problem, let's just keep doing more of the same. It at least keeps the funding flowing if there is never a solution.

This contradiction has not yet been resolved because of a lack of coronal magnetic field measurements and the limitations of idealized numerical modelling.

Whaaat? That can't be! Never heard that one before... You mean Alfvén was/is correct?

Eventually they will have to listen to Alfvén's criticism of the use of MHD models and start considering the correct physics. When will they stop relying on "models we know from experiment to be wrong "? That's the question.

The violent eruptions, called "coronal mass ejections," stem from a sudden release of magnetic energy that is stored in the sun's corona,

What is "magnetic energy"? I mean i know what particle energy is, and photons....what is the standard model "force carrier" for "magnetic energy"?

The best thing mentioned above is "Torus instability", as the only difference between these currents and those in a Tokamek is that the instability in a solar flux tube doesn't contact a reactor wall...hence a CME when the guiding field is weak.

James Chen of the Plasma Physics Division, Naval Research Laboratory, has been at the forefront of research on flares/CMEs. You can find some papers by searching.There does seem to be a correlation between the magnitude of the flare and the volume of CME material ejected.

Whyde, I am compelled to point to continuing unfair use of double standards when challenging those who point out that any current theory/hypothesis is increasingly untenable given all the past/new evidence. You just challenged cantdrive to:

Provide a viable/verifiable alternative?

Which is as CONTRARY to the SCIENTIFIC METHOD as one can be! Falsification' does NOT DEMAND "an alternative" to be offered; but ONLY that past/new evidence/discoveries contradict the theory. Period. Once falsification happens, THEN anyone may propose (if they have one) new hypothesis for testing etc. But falsification ITSELF is NOT contingent on alternative hypothesis being offered. Ok? So I'd appreciate it if you/others STOPPED implying it does. Thanks. :)

PS---CONSIDER: wherever plasma is in motion, there also are magnetic-forces & electronic 'currents' along/across/around that plasma stream. On sun we can't 'see' those currents/forces; only plasma streams/radiation. Ok? :)

@ Really-Skippy. How you are fellow Earthling? I am good, thanks for asking.

Maybe this will help,

"""These Realisations occur because fundamental relativities are infinitesimally unsettled (evidence PI etc.). This inherent flaw in the VSmatrix/Space processes means that volumetrication of direction is incomplete. Hence, flaw-related 'remainder' consequences will arise wherever the natural geometrical/mathematical operations in the 3-D Space substrate cannot execute to completion, and so fail to balance infinitesimally at all times and all places each and every intersection-point location for all the infinite totality of Direction lines-of-coincidence. In short, direction-volumetrication processes fail to close perfectly the omni-directional spheres (radial spread of direction lines-of-coincidence) effectively defining the fundamental geometrical/mathematical relativities among the totality of absolute points in the primary-vacuum Space substrate.""""

This is to make sure that credit goes to the Earthling it is due diligence to. The above stuffs I did not write but snip and glued from the Earthling Clubhouse. It was first thought up by Really-Skippy and he deserves all the credit for it not me. I don't want to get sued for plagiarism.

Oh yeah, I almost forget. If the Clubhouse crashes and you can not get in to get the good stuffs, leave me a note here because I snipped and glued and saved the whole thing here at the Louisiana Earthling Clubhouse Annex. Hooyeei, it makes you really Really-Skippy impatient for Really-Skippy's book about toes, eh? Well I sure wish he would hurry, he promised by the end of the year and that's next week.

NASA is eager to know when an eruption is coming and when what looks like the start of an outburst is just a false alarm. Knowing the difference could affect the timing of future space missions such as journeys to Mars,

Now that's really reaching. Your model will be so good to tell months in advance and so flawless that you're going to risk their lives on it??? Was this part of a primary school book report?

Wow, the abstract of that paper is literally what cantdrive parrots endlessly... word for word.

That is TOTALLY unfair to parrots. They're bright birds. They repeat things for a reason and it isn't simply to piss people off.

Ill behaved children are the best example. What a surprise. His parents really need to be sterilized and held liable for the costs they've inflicted on society. It takes some pretty spectacularly bad parenting to end up with a troll like can't think and his delusions. That's negative knowledge. I guess the apple doesn't fall far from the tree.

Uh, Gloria and Ome Henk. Kind of stupid, there. Most on here like each of you, but can't tolerate your bickering. Give it a rest, would 'ya? Ditto Otto. I'll be generous and overlook the common denominator.